PERMEABLE ELECTROCHEMICAL REACTIVE BIOBARRIER AND METHOD FOR USING THE SAME
A permeable electrochemical reactive biobarrier used to prohibit the diffusion of groundwater contaminated by organic compounds is disclosed. The permeable electrochemical reactive biobarrier includes at least a conductive fiber layer and at least a cathode. The conductive fiber layer is applied with a proper voltage, and the cathode is disposed at one side of the conductive fiber layer. Herein, the conductive fiber layer can be used as the electron acceptor for respiration occurred by local soil microorganisms, which grow on the surface of the conductive fiber layer. Accordingly, the biodegradation of organic compounds can be continued without additional oxidants.
This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 098128130 and 099127815 filed in Taiwan, Republic of China on Aug. 21, 2009 and Aug. 19, 2010, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of Invention
The present invention relates to a permeable electrochemical reactive biobarrier and, in particular, to a permeable electrochemical reactive biobarrier capable of degrading organic contaminants efficiently without adding additional chemical agents for further preventing groundwater pollution.
2. Related Art
The term of “reactive biobarrier” is one of the means to prevent contaminants distributing with the groundwater. It is established at the gas station, oil refineries, or even at some petrochemical plants to prevent the spread of groundwater polluted by organic contaminants. Practically, the reactive biobarrier is disposed perpendicularly at the downstream of polluted groundwater.
Conventional reactive biobarrier is water permeable. The principle is that when groundwater flows through the permeable reactive biobarrier, the contaminants in water are blocked by the permeable reactive biobarrier and then removed by physical methods (e.g. precipitation), chemical methods (e.g. oxidation, or reduction) or biological methods (e.g. biodegradation) to prevent the spread of polluted groundwater.
However, most physical methods exists a problem of ineffectiveness. Because the features of contaminants are not exactly the same, various contaminants cannot be removed by one physical method. Furthermore, it costs manpower and resources to remove remaining contaminants. If applying chemical methods to degrade organic contaminants, the problem of depletion and replacement of reaction agents must be considered. If applying biological degradation mechanism, how to provide sufficient electron acceptors is an existing issue. It requires a large amount of energy to supply the system and, in the meanwhile, results in uneven mass transfer easily. Accordingly, it causes the problems of replenishing or adding additional oxidants (as electron donors for microorganisms) resulting in the increase of remediation cost.
SUMMARY OF THE INVENTIONTo solve the existing issue of the conventional reactive biobarrier, a novel biobarrier is disclosed after several research and thoughts by the inventors. In detailed, the biobarrier includes a conductive fiber with large surface area and good permeability. Additionally, the relevant degrading microorganisms of the biobarrier are formed by the direct attachment and growth of local existing soil microorganisms. The biobarrier is capable of continuously degrading organic contaminants by applying a proper voltage without adding additional microorganisms and general oxidants.
An objective of the present invention is to provide a permeable electrochemical reactive biobarrier capable of degrading organic contaminants efficiently without adding additional chemical agents for preventing groundwater pollution.
To achieve the above-mentioned objective, the permeable electrochemical reactive biobarrier of the present invention includes at least a conductive fiber layer (i.e. biological anode) and a cathode. The conductive fiber layer is applied with a proper voltage, and the cathode is disposed at one side of the conductive fiber layer. Herein, the cathode is used to balance the total electronic charges.
Preferably, the conductive fiber layer is formed by a conductive carbon fiber, a metal fiber or their combination. More preferably, the conductive carbon fiber is preferably a conductive activated carbon fiber.
The present invention also discloses a method for operating a permeable electrochemical reactive biobarrier including the steps of providing the permeable electrochemical reactive biobarrier including a conductive fiber layer and a cathode; and applying a proper voltage to the permeable electrochemical reactive biobarrier. Herein, the cathode is used to balance the total electronic charges.
Preferably, the conductive fiber layer is formed by a conductive carbon fiber, a metal fiber, or their combination. More preferably, the conductive carbon fiber is preferably a conductive activated carbon fiber.
The present invention provides the permeable electrochemical reactive biobarrier for local soil microorganisms to attach and growth spontaneously. Practically, the biobarrier is capable of degrading organic contaminants effectively by just applying a proper voltage as the electron acceptors of the microorganisms instead of the conventional method of adding additional chemical oxidants. It reduces the remediation cost and provides the excellent prevention effect of groundwater pollution.
The invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein:
As shown in
The conductive activated carbon fiber layer 10 is disposed perpendicularly in the downstream of the polluted groundwater. As shown in
As also shown in
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.
Example 1 Test of Degradation Efficacy of Local Microorganisms (Using the Electrode as an Electron Acceptor)In the present example, benzene was used as a target organic contaminant (its concentration is about 350 ppm), and microorganism complex polluting soil was used as a seeding source. The test of degradation efficacy and biological current was performed in a reaction vessel. After applying with the voltage of 0.2 volts (versus an Ag/AgCl reference electrodes), it is obtained that the surface of the conductive activated carbon fiber is gradually covered by a biofilm.
In accordance with the aforementioned experiment, the reactive barrier of the present invention was expected to adapt to the condition which the benzene concentration suddenly increased about 350 ppm. It indicated the flexibility of the present invention in application.
Example 2 Stimulation Test in Soil Column for Conforming Permeable Electrochemical Reactive BiobarrierExample 2 was a test in soil column for stimulating the permeable electrochemical reactive barrier. In the present example, the height of the soil column was 45 cm, and the inner diameter of that was 3 cm. The soil column includes a conductive activated carbon fiber layer (15 cm in thickness) and a platinum (Pt) cathode disposed adjacent to the lateral sides of the conductive activated carbon fiber layer. The distance between the conductive activated carbon fiber layer and the platinum cathode was 5 cm. The test was conducted with continuous flow and hydraulic retention time thereof was within 2 days. The inflow contains the simulated contaminant such as benzene, toluene, ethybenzene and xylene (referred to briefly as BTEX), and its testing concentration was selected from about 19524, 15383, 14981 and 7257 ppb. Both of the inflow and outflow were detected for the remaining amount of BTEX. The result that more than 99% of BTEX was removed indicated the outstanding efficacy of the reactive biobarrier.
In accordance with the aforementioned two examples, the outstanding efficacy of the microorganism reactive biobarrier of the present invention has been conformed. Therefore, when the reactive biobarrier of the present invention is disposed at the downstream of groundwater polluted by organics, it can become a permeable electrochemical microorganism reactive barrier by just applying with a proper voltage (lower than 10 volt versus an Ag/AgCl reference electrodes) for the spontaneous attachment and growth of local soil microorganisms. Therefore, the conductive activated carbon fiber layer of the present invention can degrade organic contaminants effectively by just applying with a proper voltage instead of by way of adding additional chemical agents.
Claims
1. A permeable electrochemical reactive biobarrier, comprising:
- at least a conductive fiber layer applied with a proper voltage; and
- at least a cathode disposed at a side of the conductive fiber layer.
2. The permeable electrochemical reactive biobarrier of claim 1, wherein the conductive fiber layer is formed by a conductive carbon fiber, a metal fiber or their combination.
3. The permeable electrochemical reactive biobarrier of claim 2, wherein the conductive carbon fiber is a conductive activated carbon fiber.
4. A method for operating a permeable electrochemical reactive biobarrier, comprising the steps of:
- providing the permeable electrochemical reactive biobarrier including at least a conductive fiber layer and at least a cathode, wherein the cathode is disposed at a side of the conductive fiber layer; and
- applying a proper voltage to the permeable electrochemical reactive biobarrier.
5. The method of claim 4, wherein the conductive fiber layer is formed by a conductive carbon fiber, a metal fiber or their combination.
6. The method of claim 5, wherein the conductive carbon fiber is a conductive activated carbon fiber.
Type: Application
Filed: Aug 20, 2010
Publication Date: Feb 24, 2011
Inventors: Yung-Fu Wang (Kaohsiung City), Wei-Ji Chen (Tainan City), Hsu-Wen Hung (Tainan City), Po-Tseng Pan (Pingtung City), Sheng-Shung Cheng (Tainan City)
Application Number: 12/860,169
International Classification: A61L 2/03 (20060101);